1. Field of the Invention
The present invention relates to a device by which a subject, a photography condition of which should be adjusted, is selected from a plurality of objects contained in an image to be photographed, and by which a subject, which is in focus, is indicated in a viewfinder.
2. Description of the Related Art
In a photographing operation, a case may occur in which, two people, for example, are contained in an image observed through a viewfinder, however, the photographer wants to focus only on the front person, or in which the photographer wants to prevent an under-exposure of the subject which may be caused by an over-brightness of the background of the subject due to a rear light. The former case can be resolved using a focus lock, in which an in-focus condition is obtained while the camera is directed to the front person so that the front person is positioned at the center of the viewfinder frame, and then the camera is returned to the original direction to perform a shutter release. The latter case can be resolved by a rear light correction in which an exposure correction switch, provided on the camera, is operated so that an exposure of the subject image is corrected.
However, the operations of the focus lock and the rear light correction are not simple, and require a skill to some extent.
On the other hand, in a photographing operation using a single-lens reflex camera, for example, a focusing adjustment is usually carried out to an image positioned at the center of the viewfinder frame. However, since opening degrees of the aperture, i.e. a depth of field, when observing via the viewfinder frame and when performing a shutter release, are different from each other, it is difficult to recognize which area will be in focus in the taken picture, by only observing via the viewfinder frame. Therefore, conventionally, a camera is known which has a pre-view function, in which an opening degree of the aperture is changed, by operating a pre-view lever, to the amount used in the photographing operation, so that the depth of field can be observed through the viewfinder frame.
However, in the pre-view operation, since the opening degree of the aperture may be small, depending upon the brightness of the subject, the viewfinder frame may become too dark to see, and thus, it may be difficult to check the depth of field with a high accuracy.
Therefore, an object of the present invention is to provide a subject selection device, which selects a subject, for which a focus lock or a rear light correction is performed, and thus the operation, such as the focus lock and the rear light correction, can be carried out easily.
According to the present invention, there is provided a subject selection device for a camera, the device comprising a light source, an imaging device, a three-dimensional information sensing processor, a histogram generating processor and a subject selection processor.
The light source radiates a distance measuring light beam toward a plurality of objects to be photographed. Each of the objects reflects the distance measuring light beam to generate a reflected light beam. The imaging device has a plurality of photoelectric conversion elements that receive the reflected light beam, so that signal charge corresponding to an amount of the received reflected light beam is accumulated in each of the photoelectric conversion elements. The three-dimensional information sensing processor integrates the signal charge in each of the photoelectric conversion elements, whereby three-dimensional information indicating distances from the camera to points on a surface of each of the objects is obtained. The histogram generating processor generates a histogram indicating a distribution of the distances. The subject selection processor selects, based on the histogram, a subject, of which a photography condition should be adjusted, from the objects.
Further, according to the present invention, there is provided an in-focus portion indicating device for a camera, the device comprising a light source, an imaging device, a three-dimensional information sensing processor, a histogram generating processor and an in-focus portion indication processor.
The light source radiates a distance measuring light beam toward an object to be photographed, the object reflecting the distance measuring light beam to generate a reflected light beam. The imaging device has a plurality of photoelectric conversion elements that receive the reflected light beam, so that signal charge corresponding to an amount of the received reflected light beam is accumulated in each of the photoelectric conversion elements. The three-dimensional information sensing processor integrates the signal charge in each of the photoelectric conversion elements, whereby three-dimensional information indicating distances from the camera to points on a surface of the object is obtained. The histogram generating processor generates a histogram indicating a distribution of the distances. The in-focus portion indication processor indicates an in-focus portion of the object, based on a depth of field of the object and the histogram.